A highly sophisticated piece of malware has been used by malicious actors since at least 2013 to target the point-of-sale (PoS) systems of U.S. retailers, iSIGHT Partners has warned.
The malware, dubbed “ModPOS” due of its modular architecture, uses modules that are packed kernel drivers, which makes them more difficult to detect by security products. The modules identified by iSIGHT Partners so far include one for logging keystrokes, one for uploading stolen data and downloading additional components, and one for collecting card data.
ModPOS also uses several plugins to complete various tasks, such as collecting system and network information, and harvesting usernames and passwords for local and domain accounts.
Each of the modules is installed as a service and they inject malicious code into various processes to perform their intended tasks.
The keylogger module is designed to inject malicious code into the “explorer.exe” process in order to capture the victim’s keystrokes. The collected data is stored locally in a file encrypted using AES-256 with a unique encryption key generated on the system.
The uploader/downloader module is used to transfer harvested data from the infected system, and download plugins and modules from the command and control (C&C) server.
The “POS Scraper” module is designed to collect payment card track data from memory. Researchers believe the attackers target specific PoS software processes, such as “credit.exe.”
“This [process] is unique to POS vendors that use this executable as a part of their software. iSIGHT Partners is confident that the actors customize the malware based on the targeted environment,” the security firm noted in its report on ModPOS.
The modules rely on multiple methods of encryption and obfuscation to avoid detection by modern security systems. iSIGHT said it took researchers a significant amount of time to reverse engineer the threat.
iSIGHT Partners says only ModPOS’s uploader/downloader module has been detected by anti-malware products, but there hasn’t been any indication that the malicious element is related to PoS malware. Experts haven’t seen the threat in the wild, and it doesn’t appear to be sold on cybercrime forums.
Another noteworthy aspect is that the indicators of compromise (IoC) are unique on each infected system, which also contributes to the low ModPOS detection rates.
The security firm identified a small component of the threat in 2012, but the first attacks against U.S. retailers were spotted in late 2013 and continued throughout 2014. Experts say there is a high likelihood of ongoing campaigns.
“From a coding perspective, these samples are much more complex than average malware; there is professional-level coding, and the size, implemented operational security and overall characteristics of the code likely required a significant amount of time and resources to create and debug and an advanced understanding of how to undermine security identification and mitigation tools and tactics,” iSIGHT said.
Based on IP addresses and other undisclosed evidence, iSIGHT Partners believes ModPOS might have been created by Eastern European malware developers.
Several new pieces of PoS malware have been identified recently by researchers, including MalumPOS, AbaddonPOS, and Cherry Picker, a threat that managed to remain largely undetected since 2011 by cleaning up after itself.
According to Trustwave’s 2015 Global Security Report, 40 percent of the data breaches reported in 2014 were PoS-related, such systems being targeted by 70 individual variants of malware. A large majority of PoS breaches occurred due to a combination of remote access and weak passwords.